# installboot(8)

## NAME

         installboot - make a device bootable

## SYNOPSIS

         installboot -i(mage) image [label:]kernel mm fs ... init
         installboot -(e)x(tract) image
         installboot -d(evice) device bootblock boot [[label:]image ...]
         installboot -b(oot) device bootblock boot [label:]image ...
         installboot -m(aster) [fix] device masterboot

## DESCRIPTION

         Installboot may be used to make  a  device  bootable  by  constructing  a
         kernel image and installing bootstrap code into the boot block of a Minix
         file system.  To understand how this can be done one first  has  to  know
         what happens when a PC is booted.

         When the power is turned on the typical PC will try  to  read  the  first
         sector from the first floppy disk or from the first hard disk into memory
         and execute it.  The code obtained from the hard disk (from the so-called
         master  boot sector) will immediately replace itself by the code found in
         the first sector of the active partition.  Thus the PC is  now  executing
         the  bootstrap  code  found  in  the  first sector of /dev/fd0, /dev/hd1,
         /dev/hd2, /dev/hd3, or /dev/hd4.  The bootstrap will locate the operating
         system on the device it itself was loaded from, load it, and execute it.

         To make a Minix file system /dev/fd0 mounted on /mnt bootable, enter  the
         following:

              cp /usr/mdec/boot /mnt/boot

              installboot -i /mnt/minix kernel mm fs init

              installboot -d /dev/fd0 /usr/mdec/bootblock boot

         The "boot" program in the example is named the  "boot  monitor".   It  is
         loaded by the bootblock code placed in the boot sector of /dev/fd0 and it
         will take care  of  loading  the  kernel  image  "minix"  from  the  root
         directory  of  the  file system.  See monitor(8) for a description of the
         boot monitor.  Note that boot is a name in the file system on /dev/fd0 in
         this  example, the same file as /mnt/boot.  Making /mnt/minix is normally
         not necessary, there is usually a kernel image in the tools directory.

## OPTIONS

         -i(mage) image [label:]kernel mm fs ... init
              The -image option (or the  -i  shorthand)  combines  the  executable
              files  needed  to  run  Minix in one file.  Only the names and a few
              zero  bytes  are  inserted  into  the  image.   The  name   is   for
              identification  and  the  zeros  are  used to pad separate pieces to
              sector boundaries for fast loading.

              An executable may be prefixed  by  a  label.   The  monitor  may  be
              instructed  to  load  processes  by  label.  So more than one kernel
              process may  be  included  in  the  image,  each  with  a  different
              winchester  driver  for  instance.   So  if  you  have  compiled two
              different kernels with an AT or XT driver then

                   installboot -i image AT:at_kernel XT:xt_kernel mm fs init

              will make an image  with  two  different  labeled  kernels  and  one
              unlabeled set of the other binaries.

         -(e)x(tract) image
              Extract the binaries from image under the names stored in the image.
              (The name includes the optional label.)

         -d(evice) device bootblock boot [[label:]image ...]
              Installs bootblock in the boot sector of device  together  with  the
              disk  addresses  to  boot.   These disk addresses are needed to load
              boot from the file system at boot time.  The argument boot is  first
              searched  in  the file system on device.  If it is not found then it
              is read as a normal file and added at the end of  the  file  system.
              The  file system should be smaller than the device it is on to allow
              this.  Any extra images are also added to the end as described under
              -boot.  (Make sure you understand all this.)

              The device need not be mounted when installboot is run, nor does  it
              matter if it is.

              Installboot needs to be run again if boot is rewritten,  because  it
              will then occupy a new place on the disk.

              Old boot parameters are kept if there are no images added.

         -b(oot) device bootblock boot [label:]image ...
              This option fills a blank floppy in device with boot code and kernel
              images.  This "boot disk" does not have a root file system, only the
              boot monitor and Minix  kernels.   The  boot  parameters  sector  is
              filled  with  code that enables menu options for selecting an image.
              After loading an image, the monitor will ask you to  insert  a  root
              file system diskette before starting Minix.

              The labels used on the images should match those on the  executables
              used inside the image.  You can put a comma separated list of labels
              on an image for each label used within the  image.   For  the  image
              created earlier one would create a boot floppy like this:

                   installboot -b /dev/fd0 bootblock boot AT,XT:image

              If a label-list is omitted on an image,  then  that  image  will  be
              selected  by  default.   (Like  in  the  normal one image, no labels
              case.)

              Note that -device and -boot together allow you to make a boot floppy
              with  or without a root file system.  With the boot code in the file
              system, attached to the end of it, or after  the  boot  block.   And
              with  one  or more kernel images in the file system or at the end of
              the device.  Somewhat confusing.

         -m(aster) [fix] device masterboot
              This option installs the masterboot program into the boot sector  of
              the  given device.  If another device is given instead of masterboot
              then its bootstrap code is copied to device.  The  master  bootstrap
              on a hard disk boots the active partition on that disk at boot time.
              The MS-DOS fdisk command normally puts a  master  bootstrap  on  the
              hard  disk.   Minix  has two bootstraps that can be used as a master
              bootstrap.  A fairly normal  one  named  masterboot  that  works  as
              follows:

                   If the ALT key is  held  down  while  booting  then  '/dev/hd?'
                   appears  and  you  are expected to type a number key (0 - 9) to
                   select the device to boot.

                   If fix (a small number) is given then the bootstrap  is  locked
                   into booting the /dev/hdfix disk or primary partition.  This is
                   needed if 'boot *hdN' is used from the monitor to boot an  O.S.
                   that needs the active flag set.

                   If installed on a Minix floppy then it will  try  to  boot  the
                   next  floppy  or  the first hard disk.  Ideal for floppies with
                   just data on it, they will no longer obstruct the boot  process
                   if  left  in  the drive.  Also a very useful trick to boot from
                   floppy drive 1.

                   If installed on a  hard  disk  then  the  active  partition  is
                   selected  and booted as usual, unless none of the partitions is
                   marked active, then it will boot the next disk.  The latter  is
                   useful  if you want to boot an operating system from the second
                   disk by default.

              The second bootstrap is named extboot.  It has only one function, to
              boot  the  logical  partition named by fix.  Fix is not optional for
              extboot and must be a number-letter pair, like 2c for /dev/hd2c.

              Extboot or masterboot with a fix key need not be  installed  in  the
              hard disk master bootstrap per se if you don't want to mess with the
              DOS  master  bootstrap,  or  if  you  want  keep  the  active   flag
              functioning.   An  extended  partition or a non-root Minix partition
              are better candidates.  It seems  logical  to  put  extboot  in  the
              extended partition boot block.

              A backup  copy  of  the  current  master  bootstrap  (including  the
              partition table) can be made with:

                   dd if=device of=backup-file count=1

              A simple 'cat backup-file > device' will put it back.  You can  also
              use  fdisk  /mbr  under  MS-DOS 5.0 (or newer) to restore the master
              bootstrap.

## FILES

         /usr/mdec/bootblock      Minix bootstrap for the Minix root  device.   To
                                  be placed in the boot sector.

         /usr/mdec/boot           Minix Boot Monitor.  Can usually be found in the
                                  root directory of a bootable device.

         /usr/mdec/masterboot     Master bootstrap.  Can be placed  in  the  first
                                  sector of a disk to select the active partition.
                                  In a Minix  primary  partition  it  selects  the
                                  active subpartition.

         /usr/mdec/extboot        Extended partition bootstrap.

## SEE ALSO

         part(8), monitor(8).

## DIAGNOSTICS

         Boot doesn't fit on device
              If there is no space on the device  to  add  the  boot  code.   This
              usually  means that there is no boot code in the file system you use
              installboot -device on.

         Image doesn't fit on device
              If the device is too small for all the images you try to put on it.

## BUGS

         It has four more options than the SunOS installboot program it is modeled
         after.

         The bootblock code has been crunched to such ugliness that you can use it
         to scare little kids out of your garden.

## AUTHOR

         Kees J. Bot (kjb@cs.vu.nl)